Re: [PATCH 1/2] drm/i915: remove confusing GPIO vs PCH_GPIO

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

n Fri, Jul 13, 2018 at 10:48:02AM +0200, Daniel Vetter wrote:
> On Thu, Jul 12, 2018 at 08:23:05PM +0300, Ville Syrjälä wrote:
> > On Thu, Jul 12, 2018 at 07:03:58PM +0200, Daniel Vetter wrote:
> > > On Thu, Jul 12, 2018 at 6:24 PM, Lucas De Marchi
> > > <lucas.de.marchi@gmail.com> wrote:
> > > > On Thu, Jul 12, 2018 at 05:04:03PM +0200, Daniel Vetter wrote:
> > > >> On Mon, Jul 09, 2018 at 09:22:21AM -0700, Lucas De Marchi wrote:
> > > >> > Instead of defining all registers twice, define just a PCH_GPIO_BASE
> > > >> > that has the same address as PCH_GPIO_A and use that to calculate all
> > > >> > the others. This also brings VLV and !HAS_GMCH_DISPLAY in line, doing
> > > >> > the same thing.
> > > >> >
> > > >> > This also rewrites the GMBUS[05] registers since they depend on
> > > >> > gpio_mmio_base.
> > > >> >
> > > >> > v2: Fix GMBUS registers to be relative to gpio base; create GPIO()
> > > >> >     macro to return a particular gpio address and move the enum out of
> > > >> >     i915_reg.h (suggested by Jani)
> > > >> >
> > > >> > Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> > > >> > ---
> > > >> >  drivers/gpu/drm/i915/gvt/handlers.c |  2 +-
> > > >> >  drivers/gpu/drm/i915/i915_reg.h     | 53 +++++++++++++++--------------
> > > >> >  drivers/gpu/drm/i915/intel_drv.h    | 16 +++++++++
> > > >> >  drivers/gpu/drm/i915/intel_i2c.c    | 16 ++++-----
> > > >> >  4 files changed, 52 insertions(+), 35 deletions(-)
> > > >> >
> > > >> > diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
> > > >> > index e39492aaff6c..e25a74fe753b 100644
> > > >> > --- a/drivers/gpu/drm/i915/gvt/handlers.c
> > > >> > +++ b/drivers/gpu/drm/i915/gvt/handlers.c
> > > >> > @@ -2084,7 +2084,7 @@ static int init_generic_mmio_info(struct intel_gvt *gvt)
> > > >> >
> > > >> >     MMIO_F(PCH_GMBUS0, 4 * 4, 0, 0, 0, D_ALL, gmbus_mmio_read,
> > > >> >             gmbus_mmio_write);
> > > >> > -   MMIO_F(PCH_GPIOA, 6 * 4, F_UNALIGN, 0, 0, D_ALL, NULL, NULL);
> > > >> > +   MMIO_F(_MMIO(PCH_GPIO_BASE), 6 * 4, F_UNALIGN, 0, 0, D_ALL, NULL, NULL);
> > > >> >     MMIO_F(_MMIO(0xe4f00), 0x28, 0, 0, 0, D_ALL, NULL, NULL);
> > > >> >
> > > >> >     MMIO_F(_MMIO(_PCH_DPB_AUX_CH_CTL), 6 * 4, 0, 0, 0, D_PRE_SKL, NULL,
> > > >> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > > >> > index 0424e45f88db..f8f71d577613 100644
> > > >> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > >> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > >> > @@ -3088,18 +3088,11 @@ enum i915_power_well_id {
> > > >> >  /*
> > > >> >   * GPIO regs
> > > >> >   */
> > > >> > -#define GPIOA                      _MMIO(0x5010)
> > > >> > -#define GPIOB                      _MMIO(0x5014)
> > > >> > -#define GPIOC                      _MMIO(0x5018)
> > > >> > -#define GPIOD                      _MMIO(0x501c)
> > > >> > -#define GPIOE                      _MMIO(0x5020)
> > > >> > -#define GPIOF                      _MMIO(0x5024)
> > > >> > -#define GPIOG                      _MMIO(0x5028)
> > > >> > -#define GPIOH                      _MMIO(0x502c)
> > > >> > -#define GPIOJ                      _MMIO(0x5034)
> > > >> > -#define GPIOK                      _MMIO(0x5038)
> > > >> > -#define GPIOL                      _MMIO(0x503C)
> > > >> > -#define GPIOM                      _MMIO(0x5040)
> > > >> > +#define GPIO_OFFSET        0x5010u
> > > >> > +#define PCH_GPIO_BASE      (0xc0000u + GPIO_OFFSET)
> > > >> > +#define VLV_GPIO_BASE      (VLV_DISPLAY_BASE + GPIO_OFFSET)
> > > >>
> > > >> This is a rather peculiar choice of baseline address. I'd either go with
> > > >> 0x5000u or 0x0000u (which avoids the need to change all the gmbus macros).
> > > >
> > > > I'm all for a round 0x50000 number, however it doesn't match the spec.
> > > > I don't understand how 0x0 would make sense here. Are you suggesting to
> > > > embed the GPIO_OFFSET into the GPIO macro and get rid of the GPIO_BASE?
> > > >
> > > > #define GPIO_OFFSET     0x5010u
> > > > /* THESE 2 BELOW COULD USE ANOTHER BETTER NAME */
> > > > #define PCH_GPIO_BASE   0xc0000u
> > > > #define VLV_GPIO_BASE   VLV_DISPLAY_BASE
> > > > #define GPIO(gpio)      _MMIO(dev_priv->gpio_mmio_base + 0x5010 + 4 * (gpio))
> > > 
> > > Yeah that's what I had in mind.
> > 
> > I think I like this one the most. Keeps the 0x5010 in the GPIO() macro
> > so less confusion when looking it up in the spec (except on PCH platforms
> > perhaps).
> > 
> > Also I would drop the VLV_GPIO_BASE and PCH_GPIO_BASE definitions and
> > just do gpio_mmio_Base = VLV_DISPLAY_BASE/PCH_DISPLAY_BASE or something
> > like that.
> > 
> > I've occasionally pondered about some kind of generic south_display_base
> > thing that could maybe cover all the things that live on the PCH side on
> > those platforms. But I never bothered to look at all the register offsets
> > hard enough to figure out whether it'd be actually useful.
> 
> Problem with a generic south_display_base is that some things moved
> between south and north block. So not sure the generic south_display_base
> would actually be all that useful.

Yeah. And of course there are things like backlight that lives on
both sides of the divide on some platforms.

-- 
Ville Syrjälä
Intel
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